A Circadian Clock in<i>Neurospora:</i>How Genes and Proteins Cooperate to Produce a Sustained, Entrainable, and Compensated Biological Oscillator with a Period of about a Day

Dunlap, Jay C.; Loros, Jennifer J.; Colot, Hildur V.; Mehra, Arun; Belden, William J.; Shi, Mi; Hong, Christian I.; Larrondo, Luis F.; Baker, Christopher L.; Chen, C.-H.; Schwerdtfeger, Carsten; Collopy, Patrick D.; Gamsby, Joshua J.; Lambreghts, Randy

doi:10.1101/sqb.2007.72.072

Cited by 75 publications

(83 citation statements)

References 75 publications

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“…These rhythms have been well characterized in Neurospora crassa, which produces multiple bands of conidia in the dark in a circadian fashion following a single exposure to blue and/ or UVA light (Dunlap et al, 2007). Similar to N. crassa, Trichoderma spp.…”

Section: Biological Rhythmsmentioning

confidence: 99%

Reproduction without sex: conidiation in the filamentous fungus Trichoderma

et al. 2010

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2Lincoln Ventures Limited, PO Box 133, Lincoln University, Lincoln 7647, New Zealand Trichoderma spp. have served as models for asexual reproduction in filamentous fungi for over 50 years. Physical stimuli, such as light exposure and mechanical injury to the mycelium, trigger conidiation; however, conidiogenesis itself is a holistic response determined by the cell's metabolic state, as influenced by the environment and endogenous biological rhythms. Key environmental parameters are the carbon and nitrogen status and the C : N ratio, the ambient pH and the level of calcium ions. Recent advances in our understanding of the molecular biology of this fungus have revealed a conserved mechanism of environmental perception through the White Collar orthologues BLR-1 and BLR-2. Also implicated in the molecular regulation are the PacC pathways and the conidial regulator VELVET. Signal transduction cascades which link environmental signals to physiological outputs have also been revealed.

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Section: Biological Rhythmsmentioning

confidence: 99%

Reproduction without sex: conidiation in the filamentous fungus Trichoderma

et al. 2010

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“…Indeed blue-light photoreceptors and circadian clocks may have coevolved from a mechanism that originally served to detect (photoreceptor) and avoid (timer) harmful radiation (4)(5)(6). Our understanding of the molecular bases of circadian clocks and their responses to light has improved dramatically during the last decade or so, and the eukaryotic model organism Neurospora crassa has become one of the best-studied systems for understanding both processes (7)(8)(9).…”

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confidence: 99%

VIVID interacts with the WHITE COLLAR complex and FREQUENCY-interacting RNA helicase to alter light and clock responses in Neurospora

Hunt

Thompson

Elvin

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

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The photoreceptor and PAS/LOV protein VIVID (VVD) modulates blue-light signaling and influences light and temperature responses of the circadian clock in Neurospora crassa. One of the main actions of VVD on the circadian clock is to influence circadian clock phase by regulating levels of the transcripts encoded by the central clock gene frequency (frq). How this regulation is achieved is unknown. Here we show that VVD interacts with complexes central for circadian clock and blue-light signaling, namely the WHITE-COLLAR complex (WCC) and FREQUENCY-interacting RNA helicase (FRH), a component that complexes with FRQ to mediate negative feedback control in Neurospora. VVD interacts with FRH in the absence of WCC and FRQ but does not seem to control the exosome-mediated negative feedback loop. Instead, VVD acts to modulate the transcriptional activity of the WCC.ight, in addition to providing an energy source for many life forms on Earth, acts as a signal that may trigger development or serve as a repetitive cue that marks the passing of external time. External time cues are used by cellular timers such as circadian clocks to lock their periods to that of the external day. The process of period locking is called "entrainment" and ensures that cellular and behavioral activities happen at times of day when their adaptive value is highest (1-3). Blue light plays a central role in the entrainment of circadian clocks. Indeed blue-light photoreceptors and circadian clocks may have coevolved from a mechanism that originally served to detect (photoreceptor) and avoid (timer) harmful radiation (4-6). Our understanding of the molecular bases of circadian clocks and their responses to light has improved dramatically during the last decade or so, and the eukaryotic model organism Neurospora crassa has become one of the best-studied systems for understanding both processes (7-9).The key components of the Neurospora circadian clock are the products of the white collar (wc-1 and wc-2), frequency (frq), and frq-interacting helicase (frh) genes (4, 10, 11). The blue-light photoreceptor WC-1, and its interaction partner WC-2, form the transcriptionally and photoactive WHITE COLLAR complex (WCC) that activates frq expression (4, 12). FRQ protein, in turn, complexes with FRH to form an FRQ-FRH complex (FFC) that represses WCC activity (9, 11). Thus, photoreception and temporal organization of gene expression are linked via the WCC (4,(12)(13)(14). Hyperphosphorylated WCC is transcriptionally less active, and repression of WCC by FRQ occurs via FRQ-mediated phosphorylation of WCC by Casein kinase 1 and 2 (CK1 and 2) (14, 15).A second feedback loop that acts to repress WCC activity involves the product of the vivid (vvd) gene (16). Like WC-1, VVD is a PAS/LOV protein and blue-light photoreceptor; however, unlike WC-1, its presence is not essential for circadian rhythmicity in constant darkness (DD) (16)(17)(18)(19). Nevertheless, VVD has important roles within the Neurospora circadian system. Without VVD the organism is more sensitive to ...

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“…Because the light entrainment and circadian output pathways of the Neurospora systemhave been extensively reviewed elsewhere (Liu, 2003;Liu and Bell-Pedersen, 2006;Dunlap et al, 2007;Heintzen and Liu, 2007;de Paula et al, 2008), we will focus on the recent advances of the molecular mechanism of the Neurospora circadian oscillator in this review.…”

Section: Introductionmentioning

confidence: 99%

Molecular mechanism of the Neurospora circadian oscillator

Guo

Liu

2010

Protein Cell

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Circadian clocks are the internal time-keeping mechanisms for organisms to synchronize their cellular and physiological processes to the daily light/dark cycles. The molecular mechanisms underlying circadian clocks are remarkably similar in eukaryotes. Neurospora crassa, a filamentous fungus, is one of the best understood model organisms for circadian research. In recent years, accumulating data have revealed complex regulation in the Neurospora circadian clock at transcriptional, posttranscriptional, post-translational and epigenetic levels. Here we review the recent progress towards our understanding of the molecular mechanism of the Neurospora circadian oscillator. These advances have provided novel insights and furthered our understanding of the mechanism of eukaryotic circadian clocks.

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A Circadian Clock inNeurospora:How Genes and Proteins Cooperate to Produce a Sustained, Entrainable, and Compensated Biological Oscillator with a Period of about a Day

Cited by 75 publications

References 75 publications

Reproduction without sex: conidiation in the filamentous fungus Trichoderma

Reproduction without sex: conidiation in the filamentous fungus Trichoderma

VIVID interacts with the WHITE COLLAR complex and FREQUENCY-interacting RNA helicase to alter light and clock responses in Neurospora

Molecular mechanism of the Neurospora circadian oscillator

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